>> Norwegian authorities found that confusion on the Ingstad’s bridge was the immediate cause of the collision, but that the ship sank because of progressive flooding. After the collision, water quickly moved through several watertight compartments, apparently via the ship’s propeller shafts, which pass through the bulkheads between the compartments through theoretically watertight openings (known as stuffing tubes or stuffing boxes) that should prevent progressive flooding.
>> Based on crew interviews, authorities determined that the stuffing boxes weren’t working properly, jeopardising the watertightness of the ship. The investigation report warned that the faults that sunk the Ingstad could also be in other Navantia ships, raising questions about a possible problem with the design.